My company's going to want to bring Trello internal if we want to use it for confidential data. Can you bring Trello internal, by running the software on our own server?
As stated by Rich Armstrong, Director of Customer Operations
there are no plans to offer a self-hosted version in the future.
As described in their privacy section
Access to your data is tightly controlled internally. Unless we hear different from you, we will only be able to access and view the information you make public. We do run anonymous usage profiling over our database, but no one can inspect your data without your say-so.
This line does not say how well they will handle confidential data but that is a risk you are going to have evaluate based on the critical nature of your data.